The invention relates generally to implementation of services in a telecommunications network, particularly an intelligent network. The service may be any service produced in the network for a network user or another object.
The rapid evolvement of the telecommunications field has afforded operators with the capability of providing many different types of services to users. A network architecture that provides advanced services is called an intelligent network. The common abbreviation for intelligent network is IN.
The functional architecture of an intelligent network is shown in FIG. 1 where the functional entities of the network are shown as ovals. This architecture is described briefly below, because the invention will be described hereinafter with reference to the intelligent network environment.
The access of the end user (subscriber) to the network is handled by the CCAF (Call Control Agent Function). The access to the IN services is implemented by making additions to existing digital exchanges. This is done by using the basic call state model BCSM which describes the existing functionality used to process a call between two users. The BCSM is a high level state automation description of the call control functions CCF required for establishing and maintaining a connection route between users. Functionality is added to this state model by using the service switching function SSF (cf. the partial overlap of the entities CCF and SSF in FIG. 1) so that it is possible to decide when it is necessary to call the services of the intelligent network (the IN services). After these IN services have been called, the service control function SCF that contains the service logic for the intelligent network handles the service-related processing (of the call attempt). The service switching function SSF thereby connects the call control function CCF to the service control function SCF and allows the service control function SCF to control the call control function CCF. For example, SCF can request that the SSF/CCF perform specific call or connection functions, for example charging or routing operations. The SCF can also send requests to the service data function SDF which handles the access to the service-related data and network data of the intelligent network. The SCF can thus for example request the SDF to retrieve specific service-related data or update this data.
The functions described above are further complemented by the specialized resources function SRF which provides the special functions required for implementing some of the services provided by the intelligent network. Examples of these services are protocol conversions, speech recognition, voice mail, etc. The SCF can, for example, request the SSF/CCF functions to first establish a connection between the end users and SRF and then it can request the SRF to give voice announcements to the end users.
Other functional entities of the intelligent network are various functions that relate to control, such as the SCEF (Service Creation Environment Function), SMF (Service Management Function), and SMAF (Service Management Access Function). The SMF includes, among other things, service control, the SMAF provides the connection to the SMF, and the SCEF makes it possible to specify, develop, test and feed IN services via the SMF to the SCF. Because these functions only relate to the operation of the network operator, they are not shown in FIG. 1.
The role of the functional entities described in FIG. 1 as relating to the IN services will be briefly described below. The CCAF receives the service request given by the calling party. The service request usually consists of lifting the receiver and/or a series of digits dialed by the calling party. The CCAF further transmits the service request to the CCF/SSF for processing. The call control function CCF does not have the service data but it has been programmed to recognize the need of a service request. The CCF interrupts the call setup for a moment and notifies the service switching function SSF about the state of the call. The task of the SSF is, using predefined criteria, to interpret the service request and thus determine whether the request is a service request related to the IN services. If this is the case, the SSF composes a standardized IN service request and sends the request to the SCF along with information about the state of the service request. The SCF receives the request and decodes it. After that it cooperates with the SSF/CCF, SRF, and SDF to provide the requested service to the end user.
The physical level architecture of the intelligent network describes how the functional entities described above are located in the physical entities of the network. The physical architecture of the intelligent network is illustrated in FIG. 2, where the physical entities are described as rectangles or circles and functional entities as ovals. The signalling connections are described by dashed lines and the actual transport which is for example speech, by continuous lines. The optional functional entities are denoted with dashed line. The signalling network shown in the Figure is a network according to SS7 (Signalling System Number 7 is a well-known signalling system described in the CCITT (nowadays ITU-T) blue book Specifications of Signalling System No. 7, Melbourne 1988).
The subscriber equipment SE which can include, for example, a telephone, computer, or telefax, are connected either directly to a service switching point SSP or to a network access point NAP.
The service switching point SSP provides the user with access to the network and handles all necessary selection functions. The SSP can also detect any IN service requests. Functionally, the SSP includes the call control and service selection functions.
The network access point NAP is a traditional telephone exchange that includes the call control function CCF, for example, the Applicants"" DX 220 exchange which can differentiate calls that require IN services from traditional calls and route the calls that require IN services to the appropriate SSP.
The service control point SCP includes the service logic programs SLP that are used to produce the IN services. The shorter term service program will also be used for service logic programs in the following.
The service data point SDP is a database containing customer and network data which is used by the service programs of the SCP to produce tailored services. The SCP can use SDP services directly via the signalling or data network.
The intelligent peripheral IP provides special services, such as announcements and voice and multiple choice recognition.
The service switching and control point SSCP consists of an SCP and SSP located in the same network element (in other words, if the SSP network element shown in the drawing contains both an SCF and an SSF entity, the network element in question is an SSCP).
The tasks of a service management system SMP include the management of the database (SDP), network monitoring and testing, and collecting network data. It can connect to all other physical entities.
The service creation environment point SCEP is used for specifying, developing and testing the IN services, and for entering the services in SMP.
The service adjunct AD is functionally equivalent to the service control point SCP, but it is directly connected to SSP with a fast data connection (for example, with an ISDN 30B+D connection) instead of via the common channel signalling network SS7.
The service node SN can control the IN services and perform data transfers with users. It communicates directly with one or more SSPs.
The service management access point SMAP is a physical entity which provides certain users with a connection to SMP.
The above is a brief description of the intelligent network as a background to the description of the method according to the invention. The interested reader can get a more detailed description of the intelligent network in, for example, ITU-T specifications Q.121X or in the AIN specifications of Bellcore.
It should be possible to provide IN-based services to subscribers in fixed or mobile networks in a way enabling provision of tailored service in such a way that a specific subscriber-associated combination of subservices can be offered to each individual subscriber. The subservices (for which the term SF, service feature, is employed in the international standards) are the (smallest) components, visible to the customer or subscriber, that the service obtained by them comprises. The service features are termed features in the present context.
As stated previously, provisioning of a service is initiated in such a way that the SSF sends to the SCF a standard IN service request. The service request can be sent at certain stages of the call setup. The international standards, however, specify only one identifier for the service request sent by the SSF wherewith the desired service logic can be selected in the SCP. This identifier is called the service key.
The generally known technique for providing tailored services is such that the final service logic program is selected in the SCP by means of the service key value, in which case more than one values can point to the same service logic program or there may be a dedicated service logic program for each service key value. When it is desired to add services, a new version of the existing service logic program into which more service features are encoded is produced. The new version is indicated with a new service key value.
When features are concatenated to produce a new service, a feature to be added after another feature must be such that it is permissible in all situations to concatenate said features in succession. In other words, even though it is highly unlikely that a situation arises where two features cannot be applied one after the other, said features cannot be used in succession. Hence, features have been treated in the international standards in such a way that for each feature, those features that are not permissible after said feature have been classified.
Such a procedure makes implementation and commissioning of new tailored services difficult, since the features must be fashioned in such a way that they can be concatenated in succession in all situations, and on the other hand only fully complementary features can be concatenated.
It is an object of the invention to eliminate the above-described drawback and to provide a solution wherewith the implementation of new services offered in a telecommunications network can be made as flexible and diversified as possible.
This object is achieved with the method in accordance with the invention, which is defined in the independent claim.
The idea of the invention is to use a termination code at the end of an individual, newly executed feature, indicating how successful the execution of the feature was, and to select on the basis of the termination code the set of features that is possible to perform next. Thus, depending on the situation, such features can be concatenated the use of which should otherwise be prohibited entirely. Said set can comprise one or more features.
On account of the solution in accordance with the invention, new and tailored services can easily be introduced in the network on the one hand, and more diversified services than previously can be offered on the other hand.